The mission of the Toxicology Core is to provide support to Projects 1, 2 and 3 by further evaluating the toxicity of selected compounds found to have in vitro and in vivo microbicidal activity. in addition to the limited assessment of cytotoxicity performed in Projects 1 and 2, promising compounds will be extensively evaluated to determine; 1. Cell toxicity in stationary and proliferating cells; 2. Spermicidal activity; 3. Histopathological changes in genital tract tissues resulting from prolonged intravaginal usage; 4. Effect on vaginal flora; 5. Effect on fertility; 6. Mucosal immunotoxic effects.